Stationary induction apparatus.



. S.E.JOHANNESEN. STATIONARY INDUCTION-APPARATUS.

APPLICATION FILED MAY 2. 1917.

Patentd Oct. 22, 1918.

Inventor: Svenci E.Johannesen,

His Attorney- UNITED STATES PATENT OFFICE.

SVEND E. JOHANNESEN, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORIORATION OF NEW YORK.

Specification of Letters Patent.

Patented Oct. 22, 1918.

Application filed May 2,1917. Serial No, 166,023.

To all whom it may concern:

Be it known that I, Sven!) E. Jormnnnson, a citizen of the United States, residing at Pittsfield, county of Berkshire, State of Massachusetts, have invented new and useful Improvements in Stationary Induction Apparatus, of which the following is a specification.

My invention relates to various kinds of stationary induction apparatus, such as transformers, auto-transformers, some reactances, etc; for the purpose of simplicity, however, I shall hereafter refer substantially only to transformers, intending to include under that term all such related stationary induction apparatus. My invention relates particularly to transformers of the so-called distributed core type. An object of my invention is to provide an improved core.

Cores-of transformers of the distributed core typeare made up generally of a number of separate parts or units distributed substantially equiangularly about the legs carrying the windings, each core part or Section providing a leg which joins with other legs of other core parts to form a leg for a winding. My invention is directed principally toward improving the construction of the center or winding leg.

It is understood to be desirable that the space occupied by the core material of a Winding leg should be of as great cross area as possible for a given perimeter; thedegree of economy of material required for a transformer depends to a considerable extent upon the relation between the perinr eter of the core leg to be encircled by a winding to th cross area of the space within the winding occupied by the material of the core.

It is desirable therefore that the cross section of a Winding leg approach as nearly as possible a circle, since a circle has the greatest area for a given perimeter. Furthermore a Winding leg of a circular cross section, or a cross section approaching a circle,'is preferable to one in which the cre sssectlon greatly departs from a circle since a conductor surrounding a circular leg is subjected to the least bending, and bending on the longest possible radii, and hence surfers the minimum injury to its insulation by reason of the bending.

further requirement is that the core be composed of few different sizes of laminations as'possible. If more than a few sizes oflaminations are required, the device is more difiicult and expensive to manufacture, especially in the smaller sizes. By my invention it is possible to provide a core in which the winding 1c is a many-sided polygon in cross sectlon, approaching a circle, and which comprises but a very few apart about the center or winding leg, for

my invention is most applicable to sucl: a number of core units. Such a number of core units also provides considerable space between the core units for bringing out the necessary leads, taps and cross connections of'the windings and necessitates less insulation thereof than Were more core units employed.

In the accompanying drawings I have illustrated and hereinafter I have described the best forms'of my invention and certain of the best modifications thereof that I now know of; the principles of my invention will be understood therefrom.

Figure 1 is a perspective view of a three part or three unit distributed core type transformer embodying my invention. Fig. 2 is a plan view, partly in section, of the core of the transformer of Fig. 1. F 8 and 4 are plan views, partlyin section, of modifications thereof. Fig. 5 is a plan view, partly in" section, illustrating the winding leg of the transformer of Fig. 2 modified to increase the size of theaxial passage. Fig.

6 is a plan View, also partly. in section, ofa modification of the winding leg of Fig. wherein the axial passage is partially-closed. Figs. 7, 8 and 9 are plan views, also partly in section, showing further modifications of the core of Fig. 2. In'Fig. lis illustrated probably the most generally suitable form of the invention I now know of. The three parts or units 21, 22 and 23 of the core, it

Will be observed, are placed substantially equiangularly, in this caseapart, about the common inner core le 25 and the axis thereof. Each part or of the complete core comprises 'an inner leg 10, an outer leg ,11 and two yokes l2 joining the ends of the inner and outer legs. This structure provides a window or space 13 within the core fore been common .in this general type of core. The three parts or units of the trans.

former of Fig. 1 are similar and the inner legs of the three units oin and mtermesh,

as appears from the drawing, to form the inner core leg which is surrounded by the winding 15. The details of my invention will be better understood from a consideration er the remaining figures.

Each core part or unit ofthe transformer of Fig. 1 (see Fig. 2) consists of three layers of laminations 26, 27 and 28 which are indicated on the part 23 "of Fig. 2 by the lines 29 and 30 separatin' these layers. The layer 27 .may be furt er regarded as consisting of two parts 32 and 33, indicated'on this core part or unit 23 by the dividing line 34. The outer leg 11 of each core partof this particular transformer is, fanned,

that is, is provided with morelaminations or thicker laminationsthan are contained in the inner legin order that the outer leg may be operated at some lower magnetic density than the inner leg. The inner leg portion of the two part-layer 27 of each core part is made up of laminations of a uniform width, the width indicated by the length of the line 37. The part 33 of each such layer joins at its edges the other two parts 33 of the other two units at their opposite edges, thus forming the triangle 38 which is the cross section of the axial passage through the core leg. This space or passage 38 may be occupied by a bolt attaching the core clamping plates, or may be used solely as a ventilating passage for the core or otherwise, or maybe closed in any manner.

It will be observed that this triangular passage 38 is formed by reason of the facts that the laminations of each part 33 are of uniform width within the core leg and that all the laminations .of each part-layer 33 terminate in a single plane which is per.- pendicular to the planes of the laminations of the part-layer 33. The parts 32 of the layers 27 lie at one and the same side .of

their respectively adjacent parts 33. The

laminations of each of the part-layers 32 within the core leg likewise terminate in a single plane, but this plane, unlike the terminal plane of the laminations of the part-layer 33, is substantially parallel to the I planes of the laminations of the part 33 of the layer 27 of the respeetively adjacent -core part or an t; in fact the laminations of each part-lay r 32 terminate on one side unitthat is, in the construction illustrated the: laminations of the part-layer 32 of each of the two-part layers 27 terminate, or abut, against the laminations of the part-layer 33 of the similar two-part layer 27 of an adjacent core unit. Since the inner-leg laminations of the two part-layers 32 and 33 are of uniform width and terminate in two planes, the edges of these leg laminations toward the window of their respective core part likewise lie in two planes, and. it will be observed that these planes (by reason of the construction previously described) intersect in the outer surface, or the window surface, of the core leg. The layer 28 of each core part lies against the side of the layer-part 33 (of the same core part or unit) which is opposite the layer-part 32. The inner-leg laminations of the part 28 are of uniform-width and narrower than the in-. ner-leg laminations of the layer 27 as will be observed from the drawing, and terminate on the side of the adjacent core part and likewise on one side of the layer-part 32. of the respectively adjacent core part. The layer 26 lies against the side of layer 27 opposite the layer 28. The inner-leg laminations of the layer 26 are likewise narrower than the inner-leg lamina-tions of the layer 27 and also are of uniform width; the widths of the inner-leg la-minations of the layer 26 may be greater or less than, or equal to, the widths of the inner-leg laminations of the layer 28 depending upon the thicknesses (numbers of laminations) in the different layers 28, and other considerations. Preferably, however, the widths of the inner-leg laminations of the layer 26 are suclr that these laminations terminate toward the window of their respective core part (when their opposite edges terminate on the side of the adjacent core part) in the same plane as the window edges of the inner-leg laminations of the layer part 32. Also the widths of the inner-leg laminations of the layer 28 are preferably such and -.the thicknesses of the layers 26 (that is the numbers of laminations used in said layers 26) are such that the plane of the window edges of the laminations of each of the layers 28 is the plane of the adjacent side of the inner-leg portion of the respectively adjacent layer 26. Preferably also these planes intersect the planes of the window edges of the inner-leg laminations of the layer-parts 33 in the outer (or window) surface of the core leg as appears from the drawing. This consideration, it will be observed, provides a transformer core in which the center leg, which carries the winding, has for its cross section a nine sided figure. The windings may closely follow the surfaces of the winding faces, for example to provide ventilating passages. If desirable, as to provide cooling ducts for the windings or otherwise, a part of all of each layer 26 may be omitted; this idea is illustrated. and described in more detail hereinafter. It will be observed that a transformer core of the construction thus described may be constructed with relations between the widths of the laminations of the leg and the thicknesses of the layers (and part layers) of the laminations, materially-different from those shown in the drawing without however departing from the nine sided cross section. of the center leg. It is possible, therefore, to change the regu larity of the nine sided cross section and to change the equalities of the lengths of the sides of the nine sided figure. Such departures, however, may involve increasing the number of sizes (widths) of laminations required for the inner leg of each core part. It will probably be generally found preferable to so proportion the different layers that only two widths (or sizes) of inner leg laminations will be required, one size or width being used for the layers 26 and '28,

the other size being used for the layer 27.

Substantially such a relation is illustrated I in Fig. 2.

It will be observed that due to the passage 38, the cross area within the perimeter of the core leg is greater than the cross area of the material of the core leg. The magnetic flux carrying power of the core leg depends substantially entirely, of course, on the cross area of the material of the core leg, and therefore the film carrying power of the core leg 25 is reduced, as it were, by reason of the presence of the passage 38 and this passage represents so much waste space'unless this passage is used for some useful purpose as before indicated. However, even though this passage is used for no useful purpose whatsoever, the construction before described possesses such advantages over the prior art as to more than outweigh the loss of this space in a great number of cases, and where this passage threatens to assume such' proportions as to nullify the advantages of the construction, as in some of the larger sizes of the apparatus, the passage may be more or less filled with active material as hereinafter described in some detail, and its detrimental effects correspondingly reduced.

Fig. 3 illustrates a modification of the core of Fig.2 in which the layers 26 are omitted and the layers 28 built out (increased in thickness) to replace the material of the omitted layers 26. It will beobserved that the layers 28 are of such thickness (numbers of laminations) that the exp sed sides of the layers 28 lie in the same p anes as the window edges of the partdayers 32 of the respectively adj ace'nt core parts or units.

Fig. 4 illustrates a further modification; more accurately it is a modification of the core of Fig. 3, although obviously the case of Fig. 2 may be similarly modified. In the core of this figure the laminations of the part-layers 33 (of the layers 27) have been, as. it were, moved inwardly uniformly so to entirely close the triangular opening 38 of Figs. 2 and 3. This provides a space 4.1 in each core part or unit which may be used for ventilation if desired.

Fig. 5 illustrates another modification in which the laminations of the part-layers are uniformly moved outwardly to transform the triangular core passage into a hexagonal passage 52. The dotted triangle with in the opening 52 illustrates the passage as it would be had not the laminations of the part-layers 33 been moved outwardly. The

dotted lines 5% likewise illustrate the terminations of the window edges of the inner leg lamlnations of the part-layers 33 as they would be had not these laminations been moved outwardly. In this figure, however, the laminations of the part layers are shown so displaced outwardly that a part of them terminate toward their core windows 2 in the same planes as the laminations of the shaped openingwould not be sufiicient size,

for example, to admit the bolt necessary to secure the clamping plates together.

The core 0 i Fig. 6 is particularly adapted for the large sizes of transformers in which the triangular shaped passage through the core leg becomes of such size as to unduly lower the efficiency of the apparatus; this form may, however, be used in any case 'where a single fairly large passage through the core leg is unnecessary. It will be observed that the core leg of this construction differs from that of Fig. 2 particularly in the use of laminations of two widths in the layer 27. The laminations at the two sides of the layer 27 in Fig. 6 (as well as in Fig.

2) are of a. single uniform width. Contained between these side laminations of the layer 27 (in Fig. 6) are other laminations, indicated generally by 61, of greater (and also. uniform) width. The window edges of these laminations 61 terminate in the same planes. as the window edges of the remainder of the laminations of the part-layers 33. These laminations 61 consequently extend nearer the center of the core leg than the other laminations. The extension toward the core center, of'these' laminations 61 of each core part assumes a generally rectangular form, and at the maximum (as indicated in the drawing) each extension engages a similar extension of another core part and likewise the inner face of a part-layer 33 other than its own.- The maximum of the extension of the laminations 61 (if the re mainder of theconstruction is to remain unchanged) is such that the side edges of the part-layers 33 continue to engage opposite side edges of the adjacent part-layers 33 at the apexes of a substantially equilateral triangle as in this and all the preceding figures I are not similar to each other. The part 71 comprises, like the cores of Figs. 2 and 6, the

layer 27, the, layer 26 and the layer 28, and further a layer 72. The inner leg laminations of the layer 72 are, as appears from the drawing, much narrower than any of the- 7 other laminations in the core part 71. The

' tensions toward the center of the coreleg core part 73 comprises also the layers 26, 27 and 28, but the layer 27 is made up of three part-layers instead of two. A part-layer, like 32 of Fig. 2, appears at each side of the part-layer similar tothe part layer 33 of Fig. 2. The laminations of the layer 28 of core part 73 are considerably narrower than the laminations in. the layer 26 in this core part 73, and-in fact this layer 28 of narrower laminations more nearly resembles the layer 72 of the core part 71 of the present figure. In core part 75 the layer 27 comprises only a part-layer like 33 of Fig. 2, ;.the la'yers 26 and 28 lie directly against. this layer 27 as in Fig. 2. A layer 7 2 like layer 7 2 of core part 71, lies against layer 28 and terminates on the side of theadjacentcore part 71. The respective core units are provided with exsimilar'to the extensions of the laminations 61 of Fig. 6. It will be ob'served that certain laminations of layer 72 have been omitted, thereby providing ventilating spaces for the 1 coils. This omission of laminationsfor this purpose was indicated as description of Fig. 2.

Fig. 8 is as to its inner ,core' leg amodification of the core of Fig. 3 made along the same lines as'the'core of Fig. 2 (or perhaps better of Fig. 6) was modified to produce the core of Fig. 7;v the core parts or units are dissimilar as to these inner legs. The extra narrow laminations of the layers 72 of Fig. 7 do not, however, -appear in the core of Fig. 8 as illustrated; This core further distinguishes from anything shown before in that the narr ow inner-leg laminations of the possible during the different core parts or units have (Sorrel spondingly narrow outer legs, and the wider inner-leg laminations having correspondingly wide outer legs.

Fig. 9 illustrates perhaps more clearly than any of the earlier figures the result of omitting some of the laminations from the exposed sides of the core parts. This figure illustrates'the core of Fig. 3 with some of the narrower inner-leg laminations (and the corresponding yoke and outer-leg laminations) omitted, the winding of the apparatus being shown. As clearly appears, there are three ventilatingor coolingpassages 91 pr0- vided for cooling the interior of the wind.- ing. This omission of laminations also reduces the perimeter which it is necessary for the winding to surround and hence reduces the mean length of turn. The reduction in perimeter obtained by omitting certain of the laminations may in some cases be desiiable for other reasons than that of cooling the windings. i

While I have described the principle of my invention and the best mode I have contemplated for applying this principle, other modifications will occur to those skilled in this art and I aim in the appended claims to cover all modifications which do not involve a departure from the spirit and scope of my invention. It will be understood that by the; use of the term transformefiin the rality of angularly spaced parts or units,

each having a window to receive the transformer winding, the respective inner legs of the parts or units being joined to form a leg of the core, the inner leg of each of said core parts or units comprisinga layer of laminations in which laminations of a uniform width are disposed at both sides of a plane passing through the axis of said core le and terminate in the outer surface of sai core leg in a plurality of planes, and a layer of narrower laminations of uniform width lying against one side of the first mentioned layer and abutting at their inner edges against a side of an adjacent core part, said narrower laminations terminating in the outer surface of said core leg in another plane.

2. A transformer core comprising'a plurality of angularly spaced parts or units, each having a window to receive the transor the parts or units being joined to form a.

leg of the core, the inner leg of each of said former winding, the respective inner legs form width are disposed at both sides of a plane passing through the axis of said core leg and terminating in the outer surface of said core leg in a plurality of planes, and

two layers of narrower laniinations lyingatv the opposite sides of the first mentioned layer, each of said two layers being of larninations of uniform width, the, laminations of one of said layers terminating in the outer surface of said core leg in another plane.

3. A transformer core comprising a plurality of angularly spaced parts or units,

both sides of other laminations extending nearer the center of said core leg, the laminatious of said layer terminating in the outer surface of said core leg in a plurality ofplanes, and a layer of narrower laminations of uniform width lying at one side of the first mentioned layer, said narrower laniinations terminating in the outer surface of said core leg in another plane.

l. A transformer core comprising three parts or-units,"each having a window to receive the transformer winding,.the respective inner legs of the three partstor units being joined to form. a leg of the core and sai core parts or units being spaced apart suh-= stantially 120 about saidcore leg, the inner leg of each of said core parts or units comprising a layer of laminations in which v laminations of a uniform width aredisposed at both sides of a plane passing through the axis of said core leg and terminate 1n the outer surfaceof siiid core'leg in two planes,

and a la er pf'narrower laminations of 11111- rality of ang form wi th lying against one sidezof thefirst mentioned layer and abutting attheir inner edges against a side of an adjacentcore part, said narrower laminations terminating in the outer surface of said coreleg in a third plane.

, 5. A transformer core comprising three parts or units, each having awindow to receive thc'transformer winding, the respective inner legs of the three parts or units be ing joined to form a leg of thecore and said core arts or units being spaced apart substantially 120 about said core leg, the 1m ner leg comprising a layer of laminations m which laminations of a uniform Width are disposed at both sides of a lane passing through the.

axis of said core eg and terminate in the outer surface of said core leg in two planes which intersect in said surface, and two 66 layers of narrower laminations. each of said of the respectively adjacent core of each of said core parts or units.-

two layers being of laminations of uniform width, lying at the opposite sides of the first mentioned layer and each of said two layers abutting at its inner edge against a side of the respectively adjacent core part, the laminations of one of said two layers terminating in the outer surface of said core leg in a third plate intersecting one of said planes in said surface.

6. A transformer core comprising a plurality of angularly spaced parts or units, each having a window to receive the transformer winding, the respective inner legs of the core parts or units being joined to form a leg of the core, the inner leg of each of said core parts or units comprising laminations near the core part center, the edges of which at the outer surface of said core leg. lie'in a single plane, and also comprising other lan'iinations lying at the opposite sides of the first mentioned laminations, the outer edges of which lie in two other planes which intersect the first mentioned plane in the outer surface of said core leg.

7. A transformer core comprising a plurality of angularly spaced parts or units, each having a window to receive the transformer winding, the respective inner legs of the core parts or units being oined to form a leg of the core, the inner leg of each of said core parts or units" comprising laminationsfl side ofsaid layer lie in a plane which intersects the first mentioned plane in the outer surface of said core-leg and which is generally parallel to the plane of the laminations part or unit. 'mer core comprising a plurly spaced parts or units, each having a window to receive the transformer winding, the respective inner legs of the parts or units being joined to form a leg ofthe'core, the inner leg of eachof said core parts or units comprising laminations at each side thereof the edges of which at the 8. A tran outer surface of said core leg lie in a plane generally arallel to the plane of thelaminations 0;? the respectively adjacent core part or unit, each core part'or unit also comprising other. laminations between said lami-' nations at the two sides ofthe core part or unit which extend nearer the: center of said core leg than the first mentioned laminaticns and the edges of which in the surface offisgi'q core leg lie in another plane intersectin this first mentioned planes iri the surface 0E core leg.

9. A transformer core-comprising three c 180 parts'or units, each having a window to rck ceive the transformer winding, the respective inner legs of the parts or units bein joined to form a leg of the core and sai core parts or units being substantially equiangularly spaced about the said core leg, the inner leg of each core part or unit comprising laminations at both sides thereof the edges of which at the outer surface of said core leg lie in two planes at an angle of substantially 120 to each other, each core part or unit also comprising other laminations between said laminations at the two sides of the core part or unit which extend nearer the center of said coreleg than the first men tioned laminations, the outer edges of which lie in another planewhich intersects the first mentioned planes in the surface of said core leg.

10. A transformer core comprising a plurality of angularly spaced parts or units, each having a window to receive the transformer winding, the respective inner legs.

of the parts or units being joined to form a leg of the core, the inner leg of each of said core parts or units comprising a twopart layer of laminations of uniform width, the inner side edges of one part of said layer engaging opposite side edges of similar part layers of the two adjacent core parts or units, the other part of said layer abutting against one side of one of said adjacent core arts and also com risin a la er of narform width, the inner side edges of one part. of said layer engaging opposite side edgesof similar part-layers of the two adjacent core parts or units, the other part of said layer abutting against one side of one of said adjacent core parts, and also comprising a layer of narrower laminations of uniform width lying against said first mentioned layer.

12. A transformer core comprising three parts or units, each having awindow to receive the transformer winding, the respective inner legs of the parts or units being joined to form a leg of the core and said core parts or units being spaced apart substantially 120 about said core leg, the inner leg of each of said core parts or units comprising a two-part layer of laminations in which the laminations at the two sides of the layer are of uniform width, the inner side edges of one part of said layer engaging opposite side edges of similar part-layers of the other two core parts or units at the apexes of a substantially equilateral triangle, the other part of said layer abutting against a side of the adjacent core art or unit, and also comprising a layer 0 narrower laminationsof uniform width lying against said first mentioned layer and abutting against a side of the adjacent core part. i

13. A transformer core comprising three parts or units, each having a window to receive the transformer winding, the respective inner edges of the parts or units bein joined to form a leg of the core and sai core v arts or units bein spaced apart substant1ally.120 about said core leg, the inner leg of each of said core parts or units comprising a two artlayer of laminations in which the laminations at the two sides of the layer are of uniform width, the inner side edges of one part of said layer engaging opposite side edges of similar partlayers of similar layers of the other two core parts or units at the apexes of a substantially 14. A transformer core comprising a plu- I rality of angular-1y spaced parts or units, each having a window to receive the transformer winding, the respective inner legs of the parts or units being joined to form a leg of the core, the inner leg of each of said core parts or units comprising a two part layer of laminations in which'the laminations at the two sides of the layer are of uniform width, the edges of said laminations inthe outer surfacg of said leg of the. cor'e lyin in two planes which intersectin said sur ace, and a layer of narrower-laminations lying at oneside of the core part oriunit, the edges of said narrow laminations in theouter surface of said leg of the core lying in a third plane.

'15. A transformer core {comprising a plu-.

rality of angularly spaced parts or units, each having a 'window. 'for'receivii ig the transformer winding, the respective inner legs of theparts or units being joined to form a leg of the core, the inner leg of each of said core parts or units comprising a two part layer of laminations inwhich the laminations at the two sides of the layer are of uniform width and in which other laminations between said laminations of uniform width extend nearer the center of said leg, the edges of said laminations in the outer surface of said. leg of the core lying in planes which intersect in said surface, and

a layer of narrower laminations lying at one side of the core part or unit, the edges 130 of said narrower laminations in the outer surface of the said leg of the core lying in another plane.

16. A laminated core part or unit for a distributed core for electrical apparatus having an outer leg, an inner leg, and yokes joining the ends of said legs, said inner leg comprising a two part layer of laniinations in which the laminations at each of the two sides of the layer are of uniform width, the edges of said laminations toward the window of said core part or unit lying in planes which intersect in the surface of said inner leg, and a layer of narrow laniinations lying against said first mentioned layer.

17. A laminated core part or unit for a distributed core for electrical apparatus PatentOf fice.

[snnn] having an outer leg, an inner leg, and yokes joining the ends of said legs, said inner leg comprising layers of laininations the edges SVEND E. J OHANNESEN.

' It is hereby certified that in Letters Patent No. 1,282,086, granted October 22, 1918, upon the application of Svend Johannesen, of Pittsfield, Massachusetts, for an improvement in Stationary Induction Apparatus, an error appears in the printed specification requiring correction as follows: Page 5, line 73, f th d plate read plane; and that the said Letters Patent should be read with thi Signed and sealed this 10th day of December, A. D., 1918.-

F. W; H. CLAY,-

r Acting Commissioner ofgatente,

correction therein that the same may conform to the record of the casein the 

